Wild Oat Control

Beverly R. Durgan
Minnesota Extension Service Weed Scientist
HTML Editors: Jochum Wiersma & Tracy Allrich

Cultural Control

Several cultural approaches are available for wild oat control. They include: delayed small grain seeding pol\st seeding cultivation, and competitive crops.

The most practical cultural method of wild oat control is delayed small grain seeding. Delayed seeding involves an early soil cultivation to stimulate wild oat germination with one or two subsequent cultivations to control emerged wild oats prior to crop seeding. Delayed seeding, though effective in controlling wild oats, has been shown to cause up to a 40% wheat yield reduction when compared to early seeding. Also, delayed seeding may increase foxtail populations.

Planting competitive crops is another effective cultural methods for wild oat control. Barley and rye are more competitive with wild oat than spring wheat. Also, warm season row crops, such as sunflowers, soybeans, and corn should be considered in fields with heavy wild oat populations.

Many growers would like to eradicate wild oat from their fields . Research has shown that wild oat radication may not be practical or economically sound. Therefore, a combination of cultural and chemical control methods should be used to manage wild oat populations and prevent unacceptable yield losses.

Below is a summary of herbicides currently available for wild oat control in small grains.

Chemical Control

There are several herbicides available for wild oat control in spring wheat and barley. Each herbicide has advantages and disadvantages.

Good wild oat control with and herbicide requires proper timing of applications. Poster mergence wild oat herbicides require application to wild oats and crops at precise leaf stages. Leaf number on wild oats is determined by counting the leaves on the main stem and disregarding the tillers. The youngest leaf is counted as a full leaf only when another leaf becomes visible. Lower leaves which may have died from various stresses, such as frost, should be counted in the total leaf number. An accurate leaf count is important for optimum wild oat control.

Climatic conditions must also be considered when choosing a wild oat herbicide. For example, some wild oat herbicides work better under dry conditions than others. Under dry conditions, do not reduce rates below the labeled rates. The drier the conditions, the harder it is to control wild oats. Therefore, herbicides rates should probably be increased for the best control.

There are a number of tradeoffs for the advantages anyone post emergence wild oat herbicide might offer. Early wild oat control can mean better yields because the weed has less time to compete with the crop. However, when a herbicide treatment is applied early, odds are greater that a late fl;flush of wild oats will require a second herbicide application, of that some wild oats might escape treatment. Amy uncontrolled wild oats can reduce yields, and will produce seed that contribute to next year's wild oat problem. In general, under heavy wild oat pressure (over 30 plants/square foot) research has shown that a herbicide treatment should be applied as soon as possible to prevent high yield losses.

Below is a summary of the wild oat herbicides currently labeled in Minnesota.

Preemergence Wild Oat Control

Far-Go (trillate):

Far-Go (trillate) can be applied at 1 to lb/A to spring wheat and duram and at 1.25 to 1.5 lb/A to barley in the fall of spring for wild oat control. Far-Go can be applied preplant incorporated or preemergence incorporated in the spring. Far-Go is volatile and must be incorporated after application, except when applying the granule formulation in the fall. Far-Go at 1 lb/A may be applied in combination with Treflan at 0.5 to 0.75 lb/A for wild oat and foxtail control in spring wheat, duram, and barley in the spring after seeding. A package mix of Far-Go and Treflan - Buckle, can be applied in the fall or spring to land that will be planted to duram or barley. Buckle is formulated as a 13% active ingredient granule. Apply at 10 to 12.5 lb/A, incorporate after application. Use the high rate if wild oats pressure is heavy. Delayed emergence stand reduction, and stunting may occur if cold wet conditions are present during germination or crop emergence. Slight stand reductions DO NOT normally affect yield.

In research at the Northwest Experiment Station - Crookston, the granule formulation of Far-Go has given the best wild oat control, whereas liquid formulation give better control when applied in the spring.

Post Emergence Wild Oat Control

Assert (imazamethabenz):

Assert is for wild oat control in spring wheat, duram, barley and sunflowers. Assert will also give control of many plants in the mustard family, including wild mustard.

In research conducted at the Northwest Experiment Station - Crookston and the Westcentral Experiment Station - Morris, Assert has given consistent wild oat control. Spring wheat, durum and barley have good to excellent tolerance to Assert.

The use rate of Assert was lowered in 1991 to 1.0 to 1.2 pts/A. For best control, apply Assert at 1.0 to 1.2 pts/A when wild oats are in the 1 to 4-leaf stage. good wild oat control has been obtained when the 1.0 pt/A rates have been applied to 1 to 3-leaf wild oats; however, for larger wild oats, the 1.2 pt/A rate be used. The Assert formulation was also changed in 1993, and now Assert must be applied with a non-ionic surfactant at a rate of 2 pts of surfactant per 100 gallons of spray solution. For control under adverse conditions, such as dry condition or heave wild oat pressure, Assert should be applied with a crop oil concentrate at 2 pt/A in addition to the surfactant. Do not apply crop oil concentrate with 2, 4-D because of potential crop injury.

Assert can be tank mixed with 2, 4-D ester, MCPA ester, Bronate (bromoxynil + MCPA ester), Harmony Extra (tribenuron + thifensulfuron). Do not, tank mix with Banvel (dicamba), MCPA amine, or 2, 4-D amine as reduced wild oat control will result.

Assert has soil activity, and may persist for more than one year in the soil; therefore, do not plant any crop other than barley, wheat, corn, sunflowers, soybeans, or edible beans for at least 15 months after an Assert application. Do not plant sugarbeets for at least 20 months following an Assert application.

Avenge (difenzoquat):

Avenge can be used for wild oat control in spring wheat, durum or barley. Barley has good tolerance to Avenge, however, some spring wheat and durum varieties will be injured by Avenge. Many new hard red spring wheat varieties were added to the Avenge label last year, however there are still several newer varieties not listed. One variety in particular that is not on the regular Avenge label, is 2375. However, there is a supplemental label that allows Avenge to be applied to 2375 at 1/2 pts/A. 2375 will probably be planted on a large number of acres this year, however serious injury may result if Avenge is applied at rates greater than 2 1/2 pts/A. See the label for a complete list of hard red spring and durum wheat varieties that have tolerance to Avenge. Common hard red spring wheat varieties that are NOT on the Avenge label include: Sharp, Grandin, and Gus.

Avenge should be applied when the majority of wild oats are in the 3 to 5-leaf stage. In Minnesota research trials, Avenge gave the best control when wild oats were in the 4 to 5-leaf stage. Avenge should be applied at the highest labeled rate when applied to heavy infestations of 3-leaf wild oats, and should not ba applied until the wild oats have reached the 3-leaf stage. Use rate for Avenge is 2.5 to 4 pts/A.

Avenge can be tank mixed width 2,4-D, MCPA, Harmony Extra (tribenuron + thifensulfluron), Express (tribenuron), Buctril (bormoxynil), Curtail (clopyralid + 2, 4-D amine), and Bronate (bromoxynil + MCPA ester). Do not tank mix Avenge with Banvel (dicamba).

Avenge has given consistent wild oat control in the University of Minnesota research trial.

Cheyenne (fenoxaprop + MCPA ester + thifensulfuron + tribenuron)

Cheyenne:

is labeled for post emergence control of foxtails and wild oats and most annual broadleaf weeds in hard red spring wheat. Cheyenne is NOT labeled for use in durum wheat from the 3-leaf stage to the end of tillering (6-leaf stage). DO NOT apply after jointing. Apply when grass weeds are 4 inches tall or less. DO NOT tank mix Cheyenne with any other herbicide, additive, or fertilizer.

See the label for mixing instructions. Research at the University of Minnesota has shown that Cheyenne will give good to excellent control of wild oats, foxtails, kochia, common lambsquarters, pigweed and several other annual broadleaf weeds. Cheyenne Can NOT be applied by air.

There were several cases of hard red spring wheat injury due to Cheyenne applications in 1993. The injury was associated with cool, wet weather conditions and late applications. In most cases, the spring wheat recovered form this injury, and there was no yield loss. To decrease the crop injury potential, DO NOT apply Cheyenne after jointing stage. Read the label for additional restrictions or precautions.

Hoelon (diclofop):

Hoelon con be applied to all varieties of wheat, barley and durum. Hoelon should be applied when wild oats are in the 1 to 4-leaf stage. For best control. research has shown that Hoelon should be applied before the 3-leaf stage, especially when using the 2 pt/A rate. Hoelon can be applied at 2 to 3.3 pts/A (0.75 to 1.25 lb/A) in spring wheat and durum, and 2 to 2.67 pts/A (0.75 to 1.0 lb/a) in barley. Do not use over 2.67 pts/A in barley, as barley injury will result.

When using the 2 pt/A rate of Hoelon in spring wheat, barley, and durum, the addition of 1 qt/A of crop oil concentrate has been shown to increase wild oat control. DO NOT use crop oil concentrate on barley. When wild oat plants have reached the 3 to 4-leaf stage and/or plants are under moisture area stress, the higher labeled rates should be used. Wild oat control with Hoelon is increased by cool temperatures following application.

Wild oat control with Hoelon will be reduced when wild oats are growing under moisture stress. Increasing the rate used can somewhat overcome this problem.

Caution should be used before applying Hoelon to barley under the environmental conditions we have had this spring. Hoelon has the potential to give severe barley injury under cool, wet conditions. The Hoelon label states not to apply Hoelon to barley if daily minimum temperatures reach 40 degrees fahrenheit of less for three consecutive days before application. Also to mot apply when moisture content of the field is at field capacity. Hoelon should also be applied to barley before tillering.

It is important to carefully select the proper broadleaf herbicide to tank mix with Hoelon. Many broadleaf herbicides, when tank mixed with Hoelon, decrease the grass control of Hoelon. Hoelon can be tank mixed with Buctril (bromoxynil) of a low rate of MCPA ester (0.05 lb/A) plus Buctril. Do Not Tank Mix Hoelon with Harmony Extra as decreased oat control will occur. Do Not tank mix Hoelon with any other broadleaf herbicide. If a broadleaf herbicide is used, separate the Hoelon treatment and the broadleaf treatment by a minimum of 5 days.

Tiller (fenoxaprop + MCPA + 2,4-D ester):

Apply Tiller at 1.7 pts/A after the spring wheat begins to tiller (3-4 leaf stage) but prior to jointing stage (6-leaf stage) for wild oat control. Tiller will also control larger foxtail (3-leaf to 2-tillers). In University of Minnesota research, Tiller has given hood to excellent control of both yellow and green foxtail. DO NOT apply Tiller to durum wheat, barley, oats or rye. DO NOT apply more than one application of Tiller per season, or apply within 70 days of harvest. Tiller can be applied by air.

Tiller at 1.7 pts/A is labeled for tand mixing with Stinger, Buctril, and Tordon for wild oat control. Check the label for tank mixing instructions.

There were several cased of hard red spring wheat injury due to Tiller applications in 1993. The injury was associated with cool, wet weather conditions and late applications. In most cases, the spring wheat recovered from this injury, and there was no yield loss. To decrease the crop injury potential, DO NOT apply Tiller after jointing stage. Read the label for additional restrictions or precautions.

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